The present invention relates to microstructure patterns, and more particularly, to a gripping surface having a microstructure pattern adapted for improving grip on low coefficient of friction materials.
Polymer materials with low coefficient of friction (COF), such as PTFE, HDPE, nylon or POM, are manufactured into devices to allow easy sliding of devices with or without a lubricant being present. Typical examples include a PTFE shaft seal sliding against a polycarbonate housing; a nylon covered vascular catheter sliding through a polypropylene introducer tube, or a PTFE coated guide wire sliding inside a PTFE lined vascular catheter. However, these low COF items must also be gripped during manufacturing, or during use, or during disassembly and disposal. Particularly during manufacturing and use, gripping the item must be done carefully to prevent causing damage or degradation, such as creating scratches or generating contaminating particles. During high volume manufacturing, automated gripping of these materials is desirable. Current solutions for gripping low COF materials are cumbersome and require mechanical methods such as holes, slots or threads; or they accept low levels of grip force and delicate operations. It is also difficult to grip low COF rubbery polymers such as silicone rubber or human skin. Previous attempts to address these problems include unsatisfactory use of additives that results in “sticky” surfaces or use adhesives which are undesirable as they can be too sticky, create unnecessarily rough surfaces, and can cause pain to the user. The unmodified material can have a COF of 0.2 or less.
Accordingly, it is an object of the present invention to provide a microstructure arrangement on a gripping surface capable of firmly gripping low COF materials without causing damage to the material.